This application relates to our previous application Ser. No. 09/371,385, filed on Aug. 10, 1999, and entitled METHOD FOR OPTIMIZING MOBILE WIRELESS COMMUNICATIONS ROUTED ACROSS PLURAL INTERCONNECTED NETWORKS (the ""385 application), the contents of which are fully incorporated herein by this reference.
Not Applicable
1. Field of the Invention
This invention relates to the integration of voice-oriented wireless communication networks (e.g., cellular telephone systems) and data-oriented networks (e.g., Internet Protocol (IP) and Asynchronous Transfer Mode (ATM) networks). More particularly, the invention concerns the use of a data-oriented network to transport real-time communications from a first wireless communication device for information delivery to a second communication device within the context of a wireless-specific communication domain, wherein wireless-specific digital frames are transported from the first wireless communication device to and across the data-oriented network for information delivery to the second communication device in order to minimize vocoding-related traffic delays. Still more particularly, the invention is directed to a system and method for providing multi-party conferencing and tone/announcement generating functionality while nominally operating within a wireless-specific communication domain.
2. Description of the Prior Art
In the ""385 application referenced above, we disclosed a system and method for routing communication traffic between a first wireless communication device (e.g., a cellular telephone) and a second communication device (e.g., a cellular or wireline telephone) across a data-oriented network, such as an IP or ATM network. The first wireless communication device operates in a wireless network connected to the data-oriented network via an originating gateway. A terminating gateway provides access to the data-oriented network on behalf of the second communication device. In the disclosed system and method, the vocoding steps normally performed at the Base Station (BS)/Mobile Switching Center (MSC) in the wireless network, and at the originating gateway, are eliminated in order to improve call throughput efficiency and minimize transmission delays. Wireless-specific digital frames generated by vocoding circuitry in the first wireless communication device are transported as such through the BS/MSC, through the originating gateway, across the data-oriented network, and to the terminating gateway, without conversion. In this way, communication traffic originating at the first wireless communication device remains in the wireless-specific communication domain at least through the terminating gateway.
There are two considerations not discussed in the ""385 application that arise when operating in a wireless-specific communication domain. The first relates to the issue of how to provide multi-party conferencing, and the second pertains to the question of how to provide tone and announcement generation functionality on behalf of (i.e., to and from) the first wireless communication device. Implementing these functions in a conventional telephone system carrying digital Pulse Code Modulation (PCM) traffic is done by combining PCM frames to provide conferencing and to generate and transport tones and announcements over the voice channel. This technique cannot be used when the traffic is carried as wireless-specific digital frames. Relative to conferencing, one cannot combine the wireless-specific digital frames in the same manner used to combine PCM traffic frames. Similar issues arise relative to tone and announcement generation and transport to and from the first wireless communication device. With respect to tones generated by the first wireless communication device, such as dual tone multi-frequency (DTMF) patterns, the tones are encoded using wireless vocoders and transmitted in a low bit rate voice format to the vocoder at the terminating gateway. Because the tones sent in this lower bit rate format are not as accurately rendered as those sent as PCM traffic, their intended receivers (i.e., voice mail systems, automated menus, etc.) may not recognize them reliably. With respect to tones and announcements played to the first wireless communication device to implement such features as call waiting, voice mail notification, limited service area, etc., the only available source of such audio information is a database of PCM encoded frames. These PCM frames cannot be inserted into a stream of wireless-specific digital frames when playback to the first wireless communication device is required.
Accordingly, there is a need in a communication system that includes a wireless network and a data-oriented network operating in a wireless-specific communication domain, for a system and method for implementing conferencing and tone/announcement generating functionality. What is required is a system and method that allows communication to occur substantially in the wireless-specific domain while providing the ability to implement multi-party conferences and to generate tones and announcements and transmit them to and from a wireless communication device.
A solution to the foregoing problem and an advance in the art is provided by a novel system and method for implementing conferencing and tone/announcement generation functionality in a communication system that includes a wireless network and a data-oriented network operating in a wireless-specific communication domain. In this wireless-specific communication domain, wireless-specific digital frames are generated by a first wireless communication device operating in the wireless network and carried across the data-oriented network, without vocoding, for information delivery to a second communication device.
The tone generation and announcement functions of the inventive system and method are provided while retaining the wireless-specific digital frame format for traffic carried over the wireless network and the data-oriented network. The tones and announcements include tones generated by the first wireless communication device and tones and announcements delivered to the first wireless communication device. For tones generated by the first wireless communication device, signaling messages are sent directly to the terminating gateway vocoder for generation of full rate DTMF tones at the terminating network. For tones and announcements to be sent to the first wireless communication device, a wireless-encoded version of each tone and announcement is generated by a resource server that works in conjunction with a feature server, both of which are local to the wireless network. The wireless-encoded version of the tone or announcement is sent to the first wireless communication device where a corresponding audible tone or announcement is produced.
In accordance with the conferencing functions of the inventive system and method, before a composite traffic stream for conferencing can be implemented, a call using wireless-specific digital frame traffic is established between the first wireless communication device in the wireless network and the second communication device, which is assumed to be located in a first terminating network connected to the data-oriented network via a terminating gateway. A second call from the first wireless communication device to a third communication device in a second terminating network (also connected to the data-oriented network) is established using digital wireline (e.g., PCM) traffic. The second and third communication devices may be served by the same or different terminating networks (i.e., the first and second terminating networks may be the same or different). Vocoding is performed relative to the first call to convert the traffic into the same digital wireline format (e.g., PCM) used by the second call. The conference call is then implemented by combining the two calls in the conference circuit located in the wireless network serving the first wireless communication device to form a composite digital wireline traffic stream.
In preferred embodiments of the invention, the wireless network includes an MSC or MSC/BS combination (if vocoding is performed at the BS) serving the first wireless communication device. The wireless network connects to the data-oriented network through a gateway which shall be referred to as the originating gateway because the first wireless communication device is assumed to be the call originator in the call scenarios described herein. The data-oriented network is a computer data network that routes information using a network layer datagram protocol such as IP, a lower level protocol such as ATM, or both. When serving a wireline communication device, the terminating network may include a terminating End Office (EO); when serving a wireless communication device, the terminating network may include a cellular network MSC or MSC/IBS combination. Tone/announcement generation on behalf of the first wireless communication device can be supported by either 1) a wireless feature server and a packet resource server within the MSC or 2) a local data network feature server and a packet resource server located outside of the MSC (i.e., within the originating gateway). Tone generation to the second communication device is additionally provided by an enhancement to the terminating gateway whereby tones are locally generated (i.e., at the terminating gateway) on behalf of the second communication device in response to tone generation signals from the first wireless communication device. Conferencing is supported by a PCM domain conferencing circuit and vocoders (or a conferencing circuit that converts digital wireless frames internally) that allow wireless-specific communications for two-way calls but which implement normal PCM vocoding for three-way calls.
A feature server supports tones generated by the first wireless communication device and tones and announcements transmitted to the first wireless communication device. The feature server function of the present invention can be implemented within an Access Manager (e.g., Executive Cellular Processor(trademark) (ECP) from Lucent Technologies, Inc.), where the mobility and radio access server functions are also performed, or as a local data network (e.g., H.323 or System Initialization Protocol (SIP)) feature server located in the originating gateway. If the feature server is located in the ECP, the feature server will use an MSC-located packet-based resource server to generate tones and announcements in a wireless-encoded speech format (instead of PCM). A local wireless/data signaling gateway (located within the originating gateway) is also used to communicate signaling messages to and from the ECP feature server. This signaling gateway is configured to interpret feature commands usually sent by the ECP to a Digital Cellular Switch (DCS) as ECP-DCS messages, and to control a local IP switch to perform switching functions in the packet domain. The local wireless/data signaling gateway also provides interworking between the wireless routing and signaling protocol used by the ECP feature server and the data network specific (e.g., H.323 or SIP) signaling used in the data-oriented network, such that signaling messages may be exchanged between the ECP feature server and signaling resources of the data-oriented network. In the architecture that includes a local data network feature server located within the originating gateway, the feature server works in conjunction with a local data network resource server (also located within the originating gateway) to provide tones and announcements to the first wireless communication device. Under this configuration, the ECP/MSC manages wireless mobility and radio access functions, but not feature control. Feature control is provided by the local data network feature server. The local data network feature server also communicates signaling messages with signaling resources in the data-oriented network. Signaling between the ECP and a local IP switch is translated between data and wireless network signaling formats by a wireless/data signaling translator.
When a DTMF tone is generated at the first wireless communication device operating in a Global System for Mobile Communication (GSM) communication system, the first wireless communication device will be configured to recognize the tone and produce a tone generation signal. When a tone is generated at the first wireless communication device operating in a non-GSM system (e.g., TDMA or CDMA), the base station linked by radio control to the first wireless communication device will recognize the tone and produce a tone generation signal. For both GSM and non-GSM systems, the tone generation signal is sent as a signaling message to the terminating gateway, where a full rate DTMF tone is generated to the terminating network by the gateway vocoder.
Relative to tone and announcement signals sent to the first wireless communication device, the wireless-specific frame versions of the corresponding tones and announcements are stored in a database that resides in the local resource server. When the wireless-encoded tone or announcement is sent to the first wireless communication device, the audible tone or announcement is generated in the device""s vocoder.
While implementing a conference call, PCM is the preferred format for the establishment of the second call. The format of the first call after conversion is also preferably PCM. The establishment of the second call, the conversion of the first call, and the bridging of the three devices to implement conferencing are preferably performed in accordance with the H.323 and G.711 ITU standards. After the conference bridge is completed, the wireless-to-PCM vocoding in the call path from the second communication device to the conference circuit can be done in either the DCS within the MSC or in the originating gateway, or both.